DTC 00553 Questionable Signal
DTC Code 00553, Mass Air Flow Sensor G70:Questionable Signal
EGR valve N18 and MAF sensor G70 function can be checked using the Output Diagnostic Test Mode in combination with measuring value block 03. Activate the EGR valve then exit Output DTM using the "C" button. Using this sequence, the EGR valve continues to be pulsed via measuring value block 03 (channel 3). Extreme values for the MAF sensor can be read.
Special Tools, Testers And Auxiliary Items:
- VAG 1598/18 Test Box adaptor
- Fluke 83 Multimeter or equivalent
- VW 1594 Adaptor kit
- Wiring diagram
Work Sequence:
Display will appear as shown:
Rapid data transfer HELP
Select function XX
- Press 0 and 3 buttons to select Function 03 "Output Diagnostic Test Mode"
Display will appear as shown:
Rapid data transfer Q
03 - Output Diagnostic Test Mode
- Press Q button to enter input
Display will appear as shown:
Output Diagnostic Test Mode -->
Cold Start Injector N180
NOTE: Individual DTM components are only activated for 30 secs. Within this period various work sequences must be carried out with the VAG 7551 Scan Tool as well as reading the measured values. Read the following work sequence first to become familiar with the procedure before actually performing it.
- Press -> button
Display will appear as shown:
Output Diagnostic Test Mode -->
EGR Vacuum Regulator Solenoid Valve - N18
- Press C button
- Press 0 and 8 buttons to select Function 08 "Read measuring value block"
- Press Q button to enter input
Display will appear as shown:
Read measuring value block HELP
Input display group number XX
- Press 0 and 3 buttons to select "display group 03"
- Press Q button to enter input
Display will appear as shown:
Read measuring value block 3 -->
840 rpm 272 mg/H 268 mg/H 54%
Values in channels 3 and 4 must fluctuate within control range as follows:
- specification channel 3
lower region 230 to 310 mg/H
upper region 360 to 480 mg/H
- specification channel 4
lower region 2 to 5%
upper region 90 to 95%
NOTE: Scan Tool display values vary greatly. Ensure that the lowest value in channel 3 lies between 230 and 310 and the highest value lies between 360 and 480. In channel 4, the lowest value lies between 2 and 5, and the highest value lies between 90 and 95.
If specified values not obtained, check MAF sensor and EGR valve voltage supply as follows:
- Press -> button
- Press 0 and 6 buttons to select Function 06 "End data transfer"
- Press Q button to enter input
- Switch OFF ignition
- Disconnect MAF sensor -2- harness connector -1-
- Switch ON ignition
- Measure MAF sensor voltage between G70 terminals
G70 Terminal Numbers:
If specified voltages not obtained:
- Switch OFF ignition
- Connect VAG 1598/18 Test Box adaptor to ECM wiring harness connector -1-
- Check wiring for open circuit between Test Box adaptor and connector terminals using wiring diagram:
Terminal 1 + socket 19
Terminal 2 + socket 33
Terminal 3 + socket 23
Terminal 5 + socket 1
Terminal 6 + socket 13
Wire resistance: 1.5 ohm maximum
- Check for shorting between wires
Specification: infinite ohm
If specified resistances obtained, check EGR Vacuum Regulator solenoid valve N18 as follows:
- Disconnect EGR Vacuum Regulator solenoid valve -2- harness connector -1-
- Measure resistance at valve:
Specification: 14 to 18 ohm
If specified resistance not obtained:
- Replace EGR Vacuum Regulator solenoid valve N18
NOTE: At room temperature (warmer than + 15°C) resistance lies in the lower tolerance range. At Operating temperature (80°C) resistance lies in the upper tolerance range.
If specified resistance obtained:
- Check wiring for open circuit between VAG 1598/18 Test Box adaptor and harness connector using wiring diagram:
Terminal 1 + socket 68
Terminal 2 + socket 25
Wire resistance: 1.5 ohm maximum
- Check for shorting between wires
Specification: infinite ohm
If no malfunction detected:
- Replace ECM J248